This disambiguation page lists articles associated with the title UPD. If an internal link led you here, you may wish to change the link to point directly to the intended article.
Chronic smokers often have difficulty breathing because they develop Chronic Obstructive Pulmonary Disorder, or COPD. The two diseases that fall under that category are emphys â¦ ema and chronic bronchitis.
patients have difficulty breathing because air is trapped in the lungs therefore they have a hard time emptying the air out of their lungs, inspiration and expiration is effected, COPD is an example.